General lighting utilizing light-emitting diodes (LEDs) has been under development. LEDs offer several advantages over traditional light sources such as fluorescent lamps and incandescent lamps. For example, LEDs have significant lower power consumption. Unlike traditional light sources such as incandescent light bulbs that convert significant electrical current heating up the metal filaments to a temperature high enough to generate light, LEDs generate virtually no heat and utilize a fraction of the energy to produce an equivalent lumen of lighting. For example, in a light bulb application, an LED light source may consume less than 7 Watts to produce the same amount of brightness compared to an incandescent light source consuming approximately 60 Watts. In a T-8 tube application, the brightness produced by an LED light source consuming less than 20 Watts is even greater than the brightness produced by a fluorescent lamp consuming approximately 60 Watts.
The operational life of an LED is extended to 50,000 hours or even 100,000 hours. In contrast, the average life of an incandescent bulb is only approximately 5000 hours and the average life of a fluorescent lamp is approximately 15,000 hours. Moreover, LEDs contain no mercury or any other hazardous materials or chemicals and emit zero ultra violet (UV) radiation unlike incandescent or fluorescent lamps.
Dimming techniques are used to adjust the brightness of the light sources. For example, a power converter receives an AC voltage from an AC power source and generates a DC voltage to power an LED light source. A controller adjusts the output power of the power converter according to a dimmer coupled between the AC power source and the power converter in order to control dimming of the LED light source. Different dimming techniques can be used. For example, the dimmer can be a TRIAC dimmer or an on/off switch dimmer. Thus, for different types of dimmers, the controller has different structures, thereby affecting the flexibility of the controller used for powering LEDs in different dimming techniques.